At the bottom of the quarry(se)
You stand at the bottom of the pit, or as near as you can be to the bottom without getting wet. The trail you have been following disappears into the water that has flooded the bottom of the quarry. Stone walls rise high overhead all around you. The flood water forms a small lake or large pond of sorts, filling the entire bottom of the pit. There is no place left to go but back up.
The only obvious exit is southeast.